The present invention relates to dredging apparatus, and more particularly to a novel method and apparatus for removing bottom material from beneath the surface of a body of water in an automatic manner along predetermined paths.
Generally, known dredging apparatus include some type of barge construction upon which is mounted a boom member for extending a cable, with a bucket mounted thereon, over the water so that the bucket may be positioned adjacent the bottom surface of the water. The cable is power driven and additional means may be provided for operating or deploying the bucket. However, it can be readily appreciated that with a bucket suspended by a cable, no precise control in positioning the bucket adjacent the bottom surface is available. Additionally, the bucket is limited in the degree to which it can penetrate the bottom surface because there is no means for driving the bucket into the bottom other than its own weight. Of course, it can also be seen that a bucket, suspended as described above, will tend to twist or reorient, depending on the configuration or contour of the bottom surface. The result is that conventional dredging apparatus do not provide an accurate method for positioning a bucket on the bottom surface and for driving the bucket thereinto while substantially constraining the bucket from rotation about a vertical axis.
In certain dredging operations, it is desirable to accurately control the position of a bucket on the bottom surface during digging so that a predetermined, continuous path may be dredged. Unfortunately, with conventional dredging apparatus as described above, it is difficult, if not entirely impossible, to continuously position the dredge so that accurate removal of bottom material along predetermined paths may be effected. Conventional dredging apparatus generally are anchored to the bottom surface or along a shore by means of guy lines, and removal of the lines is necessary in order to reposition the dredge. Removal and repositioning of the guy lines is time consuming and burdensome and does not ensure precise relocation of the apparatus.
Additionally, in dredging operations which contemplate sand and gravel reclamation from inland pits, it is especially desirable to have a dredging apparatus which may be continuously operated along selected, predetermined paths so that bottom material may be continuously and consecutively removed over a given area. This is necessary in order to provide economically beneficial reclamation and to prevent unnecessary wastage.
Accordingly, it is a general object of the invention to provide a method and apparatus for removing material from beneath the surface of a body of water which includes a floatable base and a tower mounted thereon which extends vertically upwardly for mounting a rigid means having a bucket provided thereon. The rigid means is operable, by means of a power-driven means, for selective shifting in a substantially vertical direction to effect raising and lowering of the bucket so that the position of the bucket may be accurately controlled and also driven into the bottom surface. In order to accurately control the bucket positioning, a stabilizing means such as a carriage, is connected to the power-driven means and is shiftable in a vertical direction along vertical guides provided on the tower. The rigid means includes a pole or elongate member which extends downwardly from the carriage and upon which the bucket is mounted adjacent one end thereof.
Another object of the present invention is to provide an apparatus as described above, in which the elongate member is pivotally connected to the carriage so that it is permitted to pivotally move about a horizontal axis extending generally perpendicularly to the longitudinal axis of the elongate member. This construction provides an advantage because during downward shifting of the carriage in a vertical direction, the bucket will be driven or rammed into the bottom surface, and upon obtaining a bucket load, the base may be continuously advanced by virtue of the fact that the elongate member will swing relative to the direction of advancement.
Still another object of the present invention is to provide an apparatus, as described above, in which the bucket is pivotally connected to the elongate member for pivotal movement about another axis which also extends generally perpendicularly to the longitudinal axis of the elongate member so that the bucket may reorient depending upon the configuration of the bottom surface. Elaborating further, it can be appreciated that a typical bottom surface will have a nonuniform contour and in order for the bucket to be driven into the bottom surface so that a maximum amount of material may be obtained, it is necessary for the bucket to reorient about a generally horizontal axis of rotation so that a full bite may be taken.
Yet a further object of the present invention is to provide an apparatus, as described above, in which a first conveying means is positioned for extending over a portion of the water surface to which the base is connected. The base is operable for selective shifting therealong in a direction substantially parallel to the direction of conveyance of the first conveying means. Thus, upon shifting of the apparatus, the carriage, elongate member, and bucket may be successively advanced along a predetermined path in order to continuously remove material along the path. Advantageously, maximum material may be removed in order to more fully realize the potential of a bottom surface.
Still another object of the present invention is to provide an apparatus, as described above, further including a second conveying means disposed generally perpendicularly to said first conveying means with said first conveying means being connected thereto and operable for selective shifting along said second conveying means in a direction generally perpendicular to the direction of conveyance of the second conveying means. This construction results in an apparatus which may be selectively shifted or advanced in a first direction along the first conveying means for dredging material from the bottom surface along a predetermined path. Upon the apparatus reaching a preselected position along the first conveying means, the first conveying means may be selectively shifted along the second conveying means so that the apparatus may be shifted, in a reverse direction, along the first conveying means for dredging along a new predetermined path in a direction opposite to the first path. By suitable automatic positioning of the base relative to the first conveying means and suitable repositioning of the first conveying means relative to the second conveying means, any desired area of a bottom surface may be dredged. Advantageously, full realization of material from the bottom surface locale may be realized.
A still further object of the present invention is to provide an apparatus, as described above, in which a second carriage is provided on an opposite side of the tower which is connected to a counterweight. A cable construction, trained over winch drums, interconnects the carriages so that the counterweight facilitates raising of a loaded bucket. More particularly, it is contemplated that the second carriage and the counterweight, taken together, determine a total weight generally equal to the combined weight of the first carriage, the rigid member and the bucket together with approximately fifty percent (50%) of the weight of a bucket payload.
These and additional objects and advantages of the present invention will be more particularly understood from a consideration of the drawings and the following detailed description of the preferred embodiment.